Three-dimensional Conformal Radiation Therapy Techniques for Rectal Cancer

__Abstract__ The third most common malignancy in the Netherlands is colorectal cancer. Rectal cancer affects every year around 2000 new patients. The highest incidence is found at an age above 70 years, and in men (sex ratio: 1.48). In Europe, the treatment of preference for locally advanced rectal cancer is surgery and preoperative radiotherapy. The addition of concurrent chemotherapy is currently investigated. However, these combined modality treatments induce side effects. Diarrhea is the major side effect of (neo-)adjuvant radiation therapy for rectal cancer [3, 15]. An overview of acute and late severe bowel toxicity is given in tables 1.1-1.3

Re-irradiation: Outcome, cumulative dose and toxicity in patients retreated with stereotactic radiotherapy in the abdominal or pelvic region

The purpose of the present study was to explore the outcome, cumulative dose in tumor and organs at risk and toxicity after extra-cranial stereotactic re-irradiation. Twenty-seven patients were evaluated who had been re-irradiated with stereotactic body radiotherapy (SBRT) after conventional radiotherapy (CRT). The dose summation of the SBRT and CRT plans was done by dose point calculations accounting for fraction size by the linear-quadratic model. Efficacy and toxicity was scored by looking at the reduction in tumor size, pain and bleeding. Symptomatic response was observed in 96% of the patients. The median maximum SBRT dose to the tumor was 90 Gy3 (range: 42-420 Gy3). The median cumulative dose for the rectum, bowel and bladder resulted in 104 Gy3, 98 Gy3 and 113 Gy3, respectively. No grades 5, 4 and 3 acute and late toxicity was observed. In conclusion: Re-irradiation to the same region using extra-cranial stereotactic radiotherapy is feasible and resulted in a 96% symptomatic response with low toxicity

Single-fraction radiotherapy (SFRT) for bone metastases: Patient selection and perspectives

Bone metastases are a frequent and important source of morbidity in cancer patients. Stereotactic body radiation therapy (SBRT) is an established treatment option for local control and pain relief of bone metastases, and it is increasingly used as upfront treatment, postoperative consolidation or salvage treatment after prior RT. However, heterogeneity of dose schedules described in literature represents a severe limitation in the definition of the role of SBRT as a standard of care. No consensus is available on the use of single versus multiple fraction SBRT for bone metastases. Advantages of single-fraction SBRT include shorter overall duration of treatment, absence of inter-fraction uncertainty, improved compliance, theoretical increased efficacy, and lower costs. However, caution has been advised due to reports of severe late toxicities, in particular, vertebral collapse fracture (VCF). The aim of this paper is to review dose fractionation and indications for the management of bone metastases using SBRT

Impact of Using Unedited CT-Based DIR-Propagated Autocontours on Online ART for Pancreatic SBRT

PURPOSE: To determine the dosimetric impact of using unedited autocontours in daily plan adaptation of patients with locally advanced pancreatic cancer (LAPC) treated with stereotactic body radiotherapy using tumor tracking. MATERIALS AND METHODS: The study included 98 daily CT scans of 35 LAPC patients. All scans were manually contoured (MAN), and included the PTV and main organs-at-risk (OAR): stomach, duodenum and bowel. Precision and MIM deformable image registration (DIR) methods followed by contour propagation were used to generate autocontour sets on the daily CT scans. Autocontours remained unedited, and were compared to MAN on the whole organs and at 3, 1 and 0.5 cm from the PTV. Manual and autocontoured OAR were used to generate daily plans using the VOLO™ optimizer, and were compared to non-adapted plans. Resulting planned doses were compared based on PTV coverage and OAR dose-constraints. RESULTS: Overall, both algorithms reported a high agreement between unclipped MAN and autocontours, but showed worse results when being evaluated on the clipped structures at 1 cm and 0.5 cm from the PTV. Replanning with unedited autocontours resulted in better OAR sparing than non-adapted plans for 95% and 84% plans optimized using Precision and MIM autocontours, respectively, and obeyed OAR constraints in 64% and 56% of replans. CONCLUSION: For the majority of fractions, manual correction of autocontours could be avoided or be limited to the region closest to the PTV. This practice could further reduce the overall timings of adaptive radiotherapy workflows for patients with LAPC

Technical feasibility of online adaptive stereotactic treatments in the abdomen on a robotic radiosurgery system

BACKGROUND AND PURPOSE: Stereotactic body radiotherapy (SBRT) has been proven to be beneficial for several disease sites in the (lower) abdomen. However, the quality of the treatment plan, based on a single planning computed tomography (CT), can be compromised due to large inter-fraction motion of the target and organs at risk (OARs) in this anatomical region. The aim of this study was to investigate the feasibility of online adaptive SBRT treatments on a robotic radiosurgery system and to record estimated total treatment times. MATERIALS AND METHODS: For two disease sites, locally advanced pancreatic cancer (LAPC) and oligometastatic lymph nodes, four patients with repeat CTs were included in the feasibility study. Quick treatment plan templates were generated based on the planning CT and validated by running them on the plan and fraction CTs. For two cases a dummy run was performed and the individual steps were timed. Dose delivery was the largest contributor to the total treatment time, followed by contour adaptation. RESULTS: Running the quick plan templates resulted in plans similar to unrestricted plans, obeying the OAR constraints. The dummy runs showed that online adaptive treatments were completed in 64 to 83 min respectively for oligometastases and LAPC, comparable to other clinically available solutions. CONCLUSIONS: This study showed the feasibility of online re-planning for two challenging disease sites within a clinically acceptable time frame on a robotic radiosurgery system, making use of commercially available elements that are not integrated by the vendor

The yield of chest computed tomography in patients with locally advanced pancreatic cancer

Objective: To evaluate the incidence of pulmonary metastases on chest computed tomography (CT) in patients with locally advanced pancreatic cancer (LAPC). Methods: All patients diagnosed with LAPC in a single tertiary center (Erasmus MC) between October 2011 and December 2017 were reviewed. The staging chest CT scan and follow-up chest CT scans were evaluated. Pulmonary nodules were divided into three categories: apparent benign, too small to characterize, and apparent malignant. Results: In 124 consecutive patients diagnosed with LAPC, 119 (96%) patients underwent a staging chest CT scan at the initial presentation. In 88 (74%) patients no pulmonary nodules were found; in 16 (13%) patients an apparent benign pulmonary nodule was found, and in 15 (13%) patients a pulmonary nodule too small to characterize was found. Follow-up chest CT scan(s) were performed in 111 (93%) patients. In one patient with either no pulmonary nodule or an apparent benign pulmonary nodule at initial staging, an apparent malignant pulmonary nodule was found on a follow-up chest CT scan. However, a biopsy of the nodule was inconclusive. Of 15 patients in whom a pulmonary nodule too small to characterize was found at staging, 12 (80%) patients underwent a follow-up CT scan; in 4 (33%) of these patients, an apparent malignant pulmonary nodule was found. Conclusion: In patients with LAPC in whom at diagnosis a chest CT scan revealed either no pulmonary nodules or apparent benign pulmonary nodules, routine follow-up chest CT scans is not recommended. Patients with pulmonary nodules too small to characterize are at risk to develop apparent malignant pulmonary nodules during follow-up

Treatment selection of early stage non-small cell lung cancer: The role of the patient in clinical decision making

Background: The objective of this study is to investigate the role and experience of early stage non-small cell lung cancer (NSCLC) patient in decision making process concerning treatment selection in the current clinical practice. Methods: Stage I-II NSCLC patients (surgery 55 patients, SBRT 29 patients, median age 68) were included in this prospective study and completed a questionnaire that explored: (1) perceived patient knowledge of the advantages and disadvantages of the treatment options, (2) experience with current clinical decision making, and (3) the information that the patient reported to have received from their treating physician. This was assessed by multiple-choice, 1-5 Likert Scale, and open questions. The Decisional Conflict Scale was used to assess the decisional conflict. Health related quality of life (HRQoL) was measured with SF-36 questionnaire. Results: In 19% of patients, there was self-reported perceived lack of knowledge about the advantages and disadvantages of the treatment options. Seventy-four percent of patients felt that they were sufficiently involved in decision-making by their physician, and 81% found it important to be involved in decision making. Forty percent experienced decisional conflict, and one-in-five patients to such an extent that it made them feel unsure about the decision. Subscores with regard to feeling uninformed and on uncertainty, contributed the most to decisional conflict, as 36% felt uninformed and 17% of patients were not satisfied with their decision. HRQoL was not influenced by patient experience with decision-making or patient preferences for shared decision making. Conclusions: Dutch early-stage NSCLC patients find it important to be involved in treatment decision making. Yet a substantial proportion experiences decisional conflict and feels uninformed. Better patient information and/or involvement in treatment-decision-making is needed in order to improve patient knowledge and hopefully reduce decisional conflict

Salvage surgery for local failures after stereotactic ablative radiotherapy for early stage non-small cell lung cancer

__Introduction:__ The literature on surgical salvage, i.e. lung resections in patients who develop a local recurrence following stereotactic ablative radiotherapy (SABR), is limited. We describe our experience with salvage surgery in nine patients who developed a local recurrence following SABR for early stage non-small cell lung cancer (NSCLC). __Methods:__ Patients who underwent surgical salvage for a local recurrence following SABR for NSCLC were identified from two Dutch institutional databases. Complications were scored using the Dindo-Clavien-classification. __Results:__ Nine patients who underwent surgery for a local recurrence were identified. Median time to local recurrence was 22 months. Recurrences were diagnosed with CT- and/or 18FDG-PET-imaging, with four patients also having a pre-surgical pathological diagnosis. Extensive adhesions were observed during two resections, requiring conversion from a thoracoscopic procedure to thoracotomy during one of these procedures. Three patients experienced complications post-surgery; grade 2 (N = 2) and grade 3a (N = 1), respectively. All resection specimens showed viable tumor cells. Median length of hospital stay was 8 days (range 5-15 days) and 30-day mortality was 0 %. Lymph node dissection revealed mediastinal metastases in 3 patients, all of whom received adjuvant therapy. __Conclusions:__ Our experience with nine surgical procedures for local recurrences post-SABR revealed two grade IIIa complications, and a 30-day mortality of 0 %, suggesting that salvage surgery can be safely performed after SABR

Salvage surgery for local failures after stereotactic ablative radiotherapy for early stage non-small cell lung cancer

markdownabstract__Introduction:__ The literature on surgical salvage, i.e. lung resections in patients who develop a local recurrence following stereotactic ablative radiotherapy (SABR), is limited. We describe our experience with salvage surgery in nine patients who developed a local recurrence following SABR for early stage non-small cell lung cancer (NSCLC). __Methods:__ Patients who underwent surgical salvage for a local recurrence following SABR for NSCLC were identified from two Dutch institutional databases. Complications were scored using the Dindo-Clavien-classification. __Results:__ Nine patients who underwent surgery for a local recurrence were identified. Median time to local recurrence was 22 months. Recurrences were diagnosed with CT- and/or 18FDG-PET-imaging, with four patients also having a pre-surgical pathological diagnosis. Extensive adhesions were observed during two resections, requiring conversion from a thoracoscopic procedure to thoracotomy during one of these procedures. Three patients experienced complications post-surgery; grade 2 (N = 2) and grade 3a (N = 1), respectively. All resection specimens showed viable tumor cells. Median length of hospital stay was 8 days (range 5-15 days) and 30-day mortality was 0 %. Lymph node dissection revealed mediastinal metastases in 3 patients, all of whom received adjuvant therapy. __Conclusions:__ Our experience with nine surgical procedures for local recurrences post-SABR revealed two grade IIIa complications, and a 30-day mortality of 0 %, suggesting that salvage surgery can be safely performed after SABR